Philosophy Extract duplicate functionality from individual daemons and move it to the systemd core or the Linux kernel. Replace /etc scripts with declarative configuration files in a standard format.

One daemon to rule them all xinetd: a daemon to lazily launch internet services when activity is detected on an AF_INET socket systemd: a daemon to lazily launch any system service when activity is detected on an AF_UNIX socket (oversimplification)

systemd is: modular; asynchronous and concurrent; described by declarative sets of properties; bundled with analysis tools and tests; features a fully language-agnostic API.

Thanks Mentor Graphics for sending me to Germany to hack on systemd. Vladimir Pantelic, Tom Gundersen and Lennart Poettering for corrections of an earlier version (without implied 'ack'). Ivan Shapovalov and Mantas Mikulènas for answering questions. Bill Ward and Jym Dyer for use of their images.

photo courtesy Jym Dyer

Leftover Materials

Greg K-H: “Tightly-coupled components”

photo courtesy Bill Ward Modularity can produce complexity

systemd and outside projects: Core. OS networkd was initially contributed by Core. OS developers. Core. OS's fleet “tool that presents your entire cluster as a single init system” is based on systemd. Spin up new containers due to events on sockets. Core. OS devs are outside systemd inner circle. systemd has many patches from Arch, Intel, Debian. . .

systemd in embedded systems systemd is widely adopted in embedded systems because fastboot is required; proper allocation of resources is critical; customization of boot sequence is common. Lack of backward compatibility for older kernels (due to firmware loading) is a pain point. Embedded use cases are not always understood by systemd devs.

Override your defaults! Replace a unit in /lib (upstream) by creating one of the same name in /etc (local changes). Add services to boot by symlinking them into /etc/systemd/system/default. target. wants. 'mask' unit with link to /dev/null. Best practice: do not change the files in /lib/systemd. Read in-use unit with 'systemctl cat'. photo courtesy Jym Dyer

Crux of the problem: Dave Neary “There is no freedesktop. org process for proposing standards, identifying those which are proposals and those which are de facto implemented, and perhaps more importantly, there is no process for building consensus around a specification. . . ” (comment regarding GNOME 3)

Customizing your installation Replace a unit in /lib (upstream) by creating one of the same name in /etc (local changes). Add services to boot by symlinking them into /etc/systemd/system/default. target. wants. Best practice: do not change the files in /lib/systemd

Misconceptions systemd is more complex than sys. Vinit. systemd is full of binary configuration files. The system log is now unreadable! And liable to corruption! {Fedora/GNOME/Red. Hat/Poettering} are trying to take over all of Linux.